For the Yorkshire puddings, place the flour into a bowl, whisk in the eggs and milk until as smooth as possible then season with salt and black pepper.
Pour into a jug and place in the fridge to rest, preferably overnight.
Heat the oven to 220C/425F/Gas 7.
Place a 12 hole deep muffin tin into the oven and leave for five minutes, then add a little beef dripping into each of the holes and leave to heat for 5-10 minutes, or until smoking hot.
Take the batter from the fridge and whisk one more time. Carefully pour the batter into the tins and bake for 10-15 minutes until golden-brown and risen around the edges.
For the onion gravy, place the red wine into a wide sauté pan and heat until reduced by half. Add the stock and cook over a very low heat until reduced by half again.
Meanwhile, heat a large pan until hot then add the butter, sliced onions and thyme leaves and cook for 12-15 minutes, or until soft and lightly golden-brown.
Add the brandy and flambé to burn off the alcohol (CAUTION: Keep your face and hair away from the flames. Do not leave unattended.). Add the reduced stock and bring to the boil.
Reduce the heat to a simmer and cook for another five minutes then season with salt and freshly ground black pepper.
To serve, pour the onion gravy over the warm Yorkshire puddings.